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G. R. ELLIOTT.

PNEUMA No. 265,920. Patented Oct. 10, 1882.*

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- G. R. ELLIOTT.

- PNBUMATIG DOOR CHECK AND OLO-SER. No. 265,920. Patented Oct. l0, 1882*.l

' UNITED STATES `PATENT OEEICE.

GILEEET E. ELLIOTT, OE BOSTON, MASSACHUSETTS, ASSIeJOn TO THEl ELLIOTT PNEUMATIO DOOR cIfIEoK COMPANY, OE NASIIUA, N. H.

PNEUlVIATlC DOOR CHECK AND CLOSER.V

SPECIFICATION forming part of Letters Patent No. 265,920, dated October 1t), 1852,

Application filed April 25, 1882. (No model.) i

To all whom t may concern:

Be it known that -I, GILBERT R. ELLIOTT, a subjectof the Queen of Great Britain, residing at Boston, in the county of Suffolk and State of Ilassachusetts, have invented certain new and useful Improvements in Door-Checks; and I do hereby declare the following to be a full, clear, and exact description ot' the invention, such as will enable Others skilled in the art -to which it appertains to Inake and use the same, reference being had to the accompanying drawings, and to the letters or gures of reference marked thereon, which form apart of this specification.

This invention relates to door stops or checks, and also to devices for retaining the door in anydesired or tixed position when open.

It is well known that many devices have been made and 'adopted for the purpose of closing doors aatomatically after being opened, such as spring-hinges, spiral Springs, weights, and other eontrivances, which, as far as I am aware, have not given entire satisfaction and are in many ways objectionable. It is also well known that where such devices have been in use great annoyance is caused by slamming ofthe door against thejambs Or door-frame. not only creating very disagreeable noise, but also frequently,where thedoors are very heavy, loosening the plaster-ing and often jarring the whole side of the building. Afurther objection to the devices alluded to as at present constructed is, that when they are attached to doors it is difficult to retain the door in an open position. 'Io overcome the objections above referred to and to improve and simplify the construction, cheapen the first cost, and to make'an effective door check and stay are the objects of my invention.

To this end therefore my invention consists in certain arrangements of parts by means of which, when the door is opened, it automatically closes itself in such manner that itis prevented from slamming against the jambs, and thus avoiding the usual thud and jar and consequent noise.

It further consists in the combination, with the outer cylinder and the inner cylinder, the said cylinders being provided with projections and slots, of retaining or staying device, which will be fully hereinafter described, by which the door is held open or partly open to any deoperative.

sired extent against the tension of the spring or other closing device.

Referring to the accompanying drawings, and to the letters ot' reference marked thereon, and which form part ot' this specitication, Figure l represents a perspective view of a door and frame with my invention attached. Fig. 2 shows a longitudinal sect-ion ot' my improved double concentric cylindrical apparatus, the bracket and rack being in side elevation; Fig. 3, an external horizontal view ofthe working cylinder and bracket and slotted screw in section. Fig. 4 is an enlarged detail view ofthe slotted screw.

Like letters of reference denote like parts in all the gures.

A is the joint or door-frame. B is thedoor. C is the outer cylinder, and D the inner cylinder or trunk, (see Fie. 2),which forms in this invention a very important part.

I will here remark that heretofore great difficulty has been experienced in properly retaining the piston in true lille with its cylinder, even when the cylinder has a prolongation, but varying in diameter between the piston-bearing proper and the guiding portion ofthe cylder, for the reason that the packing is so sensitive to the air that the packing becomes dry while withdrawn from its proper bearing, and when reinserted it becomes leaky, and thus in- These two difficulties I entirely avoid t'orthe reason that the inner or trunk cylinder containing a spring has equal bearing within the outercylindcr its entire length, and thus the piston cannot get ont of line; and, secondly, it always being in close contact, its bearings are never exposed to the air, so that when once fitted it remains tightalong time.

E represents the spring, snugly fitting the bore of the inner cylinder, l), the trunk portion being so elongated that the spring, when compressed, retains a true line with the bore ofthe c) linder, and thus any shunting or twisting ot' the spring is avoided. Experience has demonstrated that when a spring is frequently and constantly strained and twisted ont of its normal condition it loses its true elasticity,

and hence my spring-holding and trunk cylinder preserves the spring and thus avoids these objections. I

F is the diaphragm or bottom of the trunkcylinder,cast solid with it, and Gr is an annnlus 

